Ok so, I realize the solution is really simple and I'm probably being a dunce. I just got the game, and when I go to install, it has 5 parts to install "Windows installer part 1 of 5" etc. When I download all 5 and run the installer for the setup it tells me that the files are corrupted and I should download a new program, help?

If you haven't used the GOG Downloader, you may want to give that a try. It downloads smaller pieces at a time and verifies each piece to make sure it was downloaded properly.

Downloading via the web browser isn't as reliable if your connection is flaky.

I didnt see an option for it, all i saw was the windows installer,

If you go into 'My Games' and select a title, there are the browser download links, or you can click a button (above the list of bonus content) to enable 'GOG.com Downloader mode' (see here).

Ok so I'm using the GoG downloader, and now it's telling me that it cannot fetch the game details and cannot download :l